The present invention relates to an improvement of pressure regulating equipment for an air cushion such as a balancer, diecushion, etc. of a press.
A balancer or a diecushion of a press generally has a large capacity reservoir storing compressed air regulated to suitable pressure, which is placed in a compressed air supply line so as to better provide a cushion effect against a shock.
The pressure regulating equipment for an air cushion of press shown in FIG. 1 was used in the past. It consisted of a pressure regulator 2, a check valve 4 with a manual override shut-off handle 3, a three way valve 5, an air reservoir 6 and a cushion cylinder 7 connected with compressed air supply lines 1 in this order.
The pressure regulator 2 used in a conventional press is constructed shown in FIG. 2, in which a valve 9b is opened or closed the by balance of force between a spring 9a pressing a diaphragm 8 downwards and air pressure of the downstream side forcing the diaphragm 8 upwards. This conventional equipment will take a long time to reach a set air pressure, as the higher the pressure of the downstream side becomes as it draws near the set pressure, opening of the valve becomes, which interrupts flowing air therethrough. It, therefore, takes as long as twenty minutes in the case of a large capacity press.
Furthermore, when the air cushion is reset to a lower pressure than the air pressure already filled up, the manual override shut-off handle 3 of the check valve 4 should be closed in order to stop flowing air into a free flowing direction, and the pressure regulator 2 should be reset to a desired pressure. Then the three way valve 5 is opened to discharge the air in the reservoir 6 until it gets a lower pressure than set pressure. The three way valve 5 is closed and the manual override handle of check valve 3 is released so that the check valve 4 works again. In this way, the pressure in the air cushion is regulated to the set pressure by pressure regulator 2. It, therefore, needs many operations to control it, which is very troublesome and takes a long time to obtain the desired pressure.